1. Field of the Invention
The present invention relates to an aqueous emulsion composition and an adherent composition and, more particularly, to an aqueous emulsion composition and an adherent composition suitably used as a primer or adhesive.
2. Description of the Prior Art
Organic solvent adhesives are generally in wide use as an adherent composition used for adhesive bonding of a variety of molded products such as plastic films, plastic sheets, plastic foams, fibers, synthetic leathers, and metals.
The organic solvent adhesives have high adhesion strength for relatively rigid molded products, so that they are used for a variety of applications, while on the other hand, they have disadvantages of being at risk of catching fire and being not so desirable in environmental sanitation. In view of these disadvantages, in recent years, aqueous adhesives have been increasingly developed as a substitute for the organic solvent adhesives.
Known as the aqueous adhesives are adherent compositions comprising ethylene-vinyl acetate copolymer containing an aqueous emulsion, for example.
However, the conventional aqueous adhesives that have been developed so far, including the adherent composition comprising ethylene-vinyl acetate copolymer containing an aqueous emulsion, are still insufficient in adhesion strength for adhesive bonding the molded products and thus are practically unusable.
It is the object of the present invention to provide an aqueous emulsion composition that has high adhesion strength for a variety of materials so that it can be used for the adhesive bonding of even molded products and to provide an adherent composition comprising the aqueous emulsion composition.
An aqueous emulsion composition of the present invention comprises a carboxyl modified resin of a saponified ethylene-vinyl acetate copolymer and a surface active agent.
The aqueous emulsion composition of the present invention can be suitably used as an adherent composition, such as a primer and an adhesive.
It is preferable that in the aqueous emulsion composition of the present invention, the carboxyl modified resin of the saponified ethylene-vinyl acetate copolymer contains the vinyl acetate in the range of 20 to 50 weight % based on the weight of raw materials used to produce the ethylene-vinyl acetate copolymer.
It is preferable that the carboxyl modified resin of the saponified ethylene-vinyl acetate copolymer has a hydroxyl value of 0-250 KOHmg/g and an acid value of 2-150 KOHmg/g.
The aqueous emulsion composition of the present invention may further comprise an unsaturated ethylene monomer or a photo polymerization initiator. The aqueous emulsion composition of the present invention may further comprise chlorinated polyolefin contained resin.
It is preferable that in the aqueous emulsion composition of the present invention, the surface active agent contains an oxyethylene group. Further, it is preferable that the surface active agent contains an anionic group. Also, it is preferable that the aqueous emulsion composition contains the surface active agent in the range of 2 to 24 parts by weight per 100 parts by weight of the carboxyl modified resin of the saponified ethylene-vinyl acetate copolymer.
An adherent composition of the present invention comprises the above-mentioned aqueous emulsion composition.
The adherent composition of the present invention comprising the aqueous emulsion composition has high adhesive strength for a variety of materials, for adhesive bonding a variety of molded products, such as plastic films, plastic sheets, plastic foams, fibers, synthetic leathers and metals. Due to the aqueous composition, the composition has little risk to catch fire and can provide good sanitation in the environment.
The aqueous emulsion composition of the present invention comprises carboxyl modified resin of saponified ethylene-vinyl acetate copolymer and surface active agent.
The carboxyl modified resin of saponified ethylene-vinyl acetate copolymer used in the present invention (hereinafter it is sometimes referred to as xe2x80x9cC-HEVAxe2x80x9d) can be produced by partly saponifying an ethylene-vinyl acetate copolymer (hereinafter it is sometimes referred to as xe2x80x9cEVAxe2x80x9d) and then modifying it by use of acid, as described, for example, by Japanese Patent Publication No. Hei 5(1993)-26,802 disclosing the production process.
The ethylene-vinyl acetate copolymer can be manufactured by a known method such as a high-pressure method and an emulsification method and is available as raw material. According to the present invention, the content of the vinyl acetate used is preferably in the range of 20 to 50 weight %, or further preferably in the range of 25 to 45 weight %, as the ratio of vinyl acetate to the raw material composition. The vinyl acetate copolymer used preferably has the melt index (g/10 min (190xc2x0 C., 2,160 g) based on ASTM D-1238 (the melt indexes occurring in the following are all the same as this)) of 0.1-500, or further preferably 1-300. The content of vinyl acetate less than that may cause reduction of flexibility and thus reduction of adhesion at low temperature. On the other hand, the content of vinyl acetate more than that may cause reduction of heat resistance.
The ethylene-vinyl acetate copolymer is saponified in the following processes. First, the ethylene-vinyl acetate copolymer is dissolved in organic solvent having a boiling point of not less than 50xc2x0 C. The organic solvents that may be used include, for example, aromatic hydrocarbons such as benzene, toluene, o-xylene, m-xylene, ethyl benzene, and propyl benzene, and aliphatic or alicyclic hydrocarbons such as n-hexane and cyclohexane. Of these organic solvents, aromatic hydrocarbon, such as xylene and toluene, being capable of causing the azeotropic boiling of water or organic solvent having a boiling point of 100-200xc2x0 C. are preferably used. While only a required amount of organic solvent to dissolve the ethylene-vinyl acetate copolymer may be used, 150-500 parts by weight of organic solvent per 100 parts by weight of ethylene-vinyl acetate copolymer should preferably be used to allow smooth progress of the next reaction.
Then, after a lower alcohol is added to the solution of ethylene-vinyl acetate copolymer thus prepared, alkali alcoholate is added thereto as catalyst in the presence of a specified amount of water, for saponification reaction.
The lower alcohols that may be used include, for example, methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, sec-butyl alcohol and tert-butyl alcohol. Methanol can preferably be cited as the lower alcohol. Preferably, the lower alcohol has the number of moles 0.1-10 times, or further preferably 1-8 times, that of the vinyl acetate contained in the ethylene-vinyl acetate copolymer, though it varies depending on the desired saponification of the ethylene-vinyl acetate copolymer.
The alkali alcoholates that may be used as the catalyst include, for example, alcoholate of alkali metal such as sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, lithium methoxide and potassium-t-butoxide. Preferably, the alkali alcoholate has the number of moles 0.01-1 times, or further preferably 0.01-0.2 times, that of the vinyl acetate contained in the ethylene-vinyl acetate copolymer, though it varies depending on the desired saponification of the ethylene-vinyl acetate copolymer.
For example, 0.1-3 moles of water per mole of alkali alcoholate is preferably used with alkali alcoholate.
The saponification may be performed by using the known condition that after a specified time (e.g. 0.5-3 hours) passing at a specified temperature (e.g. 40-60xc2x0 C.), water is added to reactive system to terminate the reaction. The degree of saponification is in the order of 10-90%, though no particular limitation is imposed thereon.
Then, the partly saponified ethylene-vinyl acetate copolymer thus produced (hereinafter it is sometimes referred to as xe2x80x9cHEVAxe2x80x9d) is modified, for example, by using acid such as unsaturated carboxylic acid or acid anhydride. It is preferable that before the partly saponified ethylene-vinyl acetate copolymer is modified by using acid, the reaction liquid used in the saponifying reaction is heated in advance to distill off the water used to terminate saponification reaction and the by-products having a low boiling point produced by the reaction, so as to remove them. Particularly when the acid anhydride is used as the acid, it is necessary to substantially remove water. This is because water in the reaction system would hinder the modification reaction.
When the unsaturated carboxylic acid is used for modification, the unsaturated carboxylic acid is added to reaction liquid and heated in the presence of radical formation substance, for the modification reaction. The unsaturated carboxylic acid that may be used include, for example, unsaturated monocarboxylic acid or unsaturated dicarboxylic acid, such as acrylic acid, methacrylic acid, crotonic acid and itaconic acid. Preferably, not more than 5 parts by weight, or preferably 0.2-3 parts by weight, of unsaturated carboxylic acid is used per 100 parts by weight of partly saponified ethylene-vinyl acetate copolymer.
The radical formation substance is the substance that is easily decomposed at the reaction temperature for modification reaction to form free radical. The radical formation substances include, for example, organic peroxide, such as benzoyl peroxide, lauroyl peroxide and dicumyl peroxide, and nitrogen containing compound such as xcex1, xcex1xe2x80x2-azobisisobutyronitrile. Preferably, 0.05-3 parts by weight, or preferably 0.01-1 parts by weight, of radical formation substance is used per 100 parts by weight of partly saponified ethylene-vinyl acetate copolymer.
The heating temperature is preferably in the range of about 50 to about 150xc2x0 C., through it varies depending on types of unsaturated carboxyl acids and organic solvents used, and the heating time is preferably in the range of about 0.1 to 5 hours.
When the acid anhydride is used for modification, the acid anhydride is added to the reaction liquid and heated, for the modification reaction. The acid anhydrides that may be used include, for example, saturated or unsaturated, aliphatic, alicyclic or aromatic anhydride, such as maleic anhydride, succinic anhydride, glutaric anhydride, phthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophtalic anhydride, tetrahydrophtalic anhydride, methyltetrahydrophtalic anhydride and trimellitic anhydride. Preferably, not more than 150 parts by weight, or preferably 10-100 parts by weight, of acid anhydride is used per 100 parts by weight of partly saponified ethylene-vinyl acetate copolymer. Preferably, 5-100 mol %, or preferably 50-100 mol %, of the vinyl alcohol unit contained in the partly saponified ethylene-vinyl acetate copolymer is estelified by using this specified amount of acid anhydride.
The heating temperature is preferably in the range of about 50 to about 150xc2x0 C., through it varies depending on types of acid anhydrides and organic solvents used, and the heating time is preferably in the range of about 0.1 to 5 hours.
Preferably, the carboxyl modified resin of the saponified ethylene-vinyl acetate copolymer thus produced has the acid value of 2-150 KOHmg/g, or further preferably 3-100 KOHmg/g, and the hydroxyl value of 0-250 KOHmg/g, or further preferably 0-160 KOHmg/g.
The acid value less than that may cause reduction of adhesion properties, while on the other hand, the acid value more than that may cause reduction of water resistance. The hydroxyl value more than that may cause cohesive force and reduction of adhesion properties at low temperature.
The surface active agent used in the present invention is not limited to any particular one. Any known surface active agent may be used. The surface active agents that may be used include, for example, anionic surface active agents, such as fatty acid salt, alkyl sulfate, alkyl benzene sulfate, alkyl sulfosuccinate, polyoxyalkylene alkylether sulfate, polyoxyalkylene alkylether carboxylate and polyoxyalkylene alkylether phosphate, cationic surface active agents, such as alkylamine salt and quaternary ammonium salt, and nonionic surface active agents, such as polyoxyalkylene alkyl ether, polyoxyalkylene alkylphenyl ether and sorbitan fatty acid ester. In the present invention, the surface active agent having an oxyethylene group is preferably used. The surface active agents having the oxyethylene groups include, for example, polyoxyethylene surface active agent, such as polyoxyethylene alkylether sulfate, polyoxyethylene alkylether, polyoxyethylene alkylphenylether, polyoxyethylene sorbitan fatty acid ester and derivatives of other polyoxyethylene. Of these polyoxyethylene surface active agents, a polyoxyethylene surface active agent having an anionic group is preferable. For example, polyoxyethylene alkylether sulfate can be cited as the polyoxyethylene surface active agent having anionic group.
These surface active agents may be used singly or in combination of two or more. Preferably, 0.5-30 parts by weight, preferably 2-24 parts by weight, or further preferably 5-20 parts by weight, of surface active agent is used per 100 parts by weight of carboxyl modified resin of the saponified ethylene-vinyl acetate copolymer. The amount of surface active agent less than that may cause reduction of dispersibility, while on the other hand, the amount of surface active agent more than that may cause reduction of adhesion properties.
The aqueous emulsion composition of the present invention can be produced by the process that after the carboxyl modified resin of the saponified ethylene-vinyl acetate copolymer and the surface active agent are mixed in the proportion specified above, the mixture is emulsified by adding water thereto.
Preferably, 50-1,000 parts by weight, or preferably 100-500 parts by weight, of water is added per 100 parts by weight of the mixture.
Emulsification may be effected by any known process. For example, the mixture to which water is added may be agitated to be forcibly emulsified. In this emulsification, a remaining organic solvent contained in the carboxyl modified resin of the saponified ethylene-vinyl acetate copolymer is preferably distilled off by the azeotropic boiling of water.
Preferably, the aqueous emulsion composition thus produced is finally prepared in the solid content of 5-70 weight %, or preferably 10-50 weight %.
Unsaturated ethylene monomer may be mixed in the aqueous emulsion composition thus produced. The adhesion properties can properly be adjusted by the mixture of the ethylene unsaturated monomer.
For example, monofunctional monomer, difunctional monomer and polyfunctional monomer may be used as the ethylene unsaturated monomer.
The monofunctional monomers (monofunctional polymerization diluents) include, for example, heterocyclic ethylene unsaturated compound (e.g. N-vinyl-nitrogen-contained heterocyclic compound, such as N-vinylpyrolidone, N-vinylpyridine and N-vinylcaprolactam, and heterocyclic (metha) acrylate, such as morpholine (metha) acrylate and tetrahydrofurfuryl (metha) acrylate), N-vinylformamide, N-vinylacetamide, dialkyl aminoethyl (metha) acrylate (e.g. dimethyl aminoethyl (metha) acrylate and diethyl aminoethyl (metha) acrylate), N, Nxe2x80x2-dimethyl acrylamide, alkoxy (poly) alkylene glycol (metha) acrylate (e.g. methoxy ethylene glycol (metha) acrylate, methoxy polyethylene glycol (metha) acrylate and butoxy polyethylene glycol (metha) acrylate), alkylphenoxyethyl (metha) acrylate (e.g. nonyl phenoxyethyl (metha) acrylate), phenoxy (poly) alkylene glycol (metha) acrylate (e.g. phenoxyethyl (metha) acrylate and phenoxypolyethylene glycol (metha) acrylate), alkyl (metha) acrylate (e.g. butyl (metha) acrylate and 2-ethylhexyl (metha) acrylate), cycloalkyl (metha) acrylate (e.g. cyclohexyl (metha) acrylate), aralkyl (metha) acrylate (e.g. benzyl (metha) acrylate), (metha) acrylate having crosslinked cyclic hydrocarbon group (e.g. isobornyl (metha) acrylate, dicyclopentadiene (metha) acrylate, dicyclopentenyl (metha) acrylate, tricyclodecanyl (metha) acrylate, dicyclopentenyloxyalkyl (metha) acrylate, tricyclodecanyloxyethyl (metha) acrylate and isobornyloxyethyl (metha) acrylate), hydroxyl group contained (metha) acrylate (e.g. 2-hydroxyethyl (metha) acrylate, 2-hydroxypropyl (metha) acrylate, 3-chloro-2-hydroxypropyl (metha) acrylate, 2-hydroxy-3-phenyloxypropyl (metha) acrylate, 2-(metha) acryloyloxyethyl-2-hydroxyethyl phthalate, 3-acryloyloxyglycerinmono (metha) acrylate, 2-hydroxybutyl (metha) acrylate, 4- hydroxybutyl (metha) acrylate, pentanediolmono (metha) acrylate, 2-hydroxyalkyl (metha) acryloyl phosphate, 4-hydroxycyclohexyl (metha) acrylate, neopenthyl glycol mono (metha) acrylate, polypropylene glycol mono (metha) acrylate, and polyethylene glycol mono (metha) acrylate), poly xcex5-caprolactone mono (metha) acrylate, glycidyl (metha) acrylate, mono[2-(metha) acryloyloxyethyl] acid phosphate, halogen contained (metha) acrylate (e.g. trifluoroethyl (metha) acrylate, 2,2,3,3-tetrafluoropropyl (metha) acrylate, 2,2,3,4,4,4-hexafluorobutyl (metha) acrylate and perfluorooctylethyl (metha) acrylate).
The difunctional monomers (difunctional polymerization diluents) include, for example, di(metha)acrylate of 2,2-dimethyl-3-hydroxypropyl-2,2-dimethyl-3-hydroxypropionate, (polyoxy) alkylene glycol di (metha) acrylate (e.g. ethylene glycol di (metha) acrylate, diethylene glycol di (metha) acrylate, tetraethylene glycol di (metha) acrylate, polyethylene glycol di (metha) acrylate, propylene glycol di (metha) acrylate, polypropylene di (metha) acrylate, 1,4-butandiol di (metha) acrylate, 1,6-hexandiol di (metha) acrylate, neopentyl glycol di (metha) acrylate and pentanediol di (metha) acrylate), glycerin di (metha) acrylate, trimethylolpropane di (metha) acrylate, pentaerythritol di (metha) acrylate, di (metha) acrylate of bisphenol A of alkyleneoxide (ethylene oxide, propylene oxide) adduct (e.g. di (metha) acrylate of 2,2-bis (2-hydroxyethoxyphenyl) propane), di (metha) acrylate having crosslinked cyclic hydrocarbon group (e.g. di (metha) acrylate of tricyclodecane dimethylol, dicyclopentadiene di (metha) acrylate), and (metha) acrylic acid adduct of difunctional epoxy resin (e.g. (metha) acrylic acid adduct of 2,2-bis (glycidyloxyphenyl) propane).
The polyfunctional monomers (polyfunctional polymerization diluents) include, for example, trimethylolpropane tri (metha) acrylate, trimethylolpropane trioxy tri (metha) acrylate, pentaerythritol tetra (metha) acrylate, dipentaerythritol hexa (metha) acrylate, tetramethylolmethane tri (metha) acrylate, tetramethylolmethane tetra (metha) acrylate, tris (acryloyloxy) isocyanurate, tri (metha) acrylate of tris (2-hydroxyethyl) isocyanurate, tri (metha) acrylate of tris (hydroxypropyl) isocyanurate, triallyl trimellitic acid and triallyl isocyanurate.
These ethylene unsaturated monomers may be used singly or in combination of two or more. Preferably, 1-200 parts by weight of the total amount of ethylene unsaturated monomer is used per 100 parts by weight of carboxyl modified resin of the saponified ethylene-vinyl acetate copolymer.
Also, a photo polymerization initiator may be mixed in the aqueous emulsion composition thus produced. The photo polymerization initiators that may be used include, for example, the photo polymerization initiators of acylphosphineoxide, of acetophenone, of benzoinether, of benzophenone and of thioxantone.
The acylphosphineoxide photo polymerization initiators include, for example, 2,4,6-trimethylbenzoyl diphenylphosphineoxide (e.g. Lucirin TPO available from BASF Aktiengesellshaft), bis (2,6-dimethoxybenzoyl)-2,4,4-trimethylpenthyl phosphineoxide (BAPO), bis (2,4,6-trimethylbenzoyl) phenylphosphineoxide, bis (2,4,6-trimethylbenzoyl) ethylphosphineoxide, and bis (2,4,6-trimethylbenzoyl) n-butylphosphineoxide.
The acetophenone photo polymerization initiators include, for example, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenyl-1-propanone (e.g. Darocur 1173 available from Ciba Specialty Chemicals), benzildimethyl ketal (e.g. Irgacure 651 available from Ciba Specialty Chemicals, Lucirin BDK available from BASF Aktiengesellshaft etc.), 1-hydroxy-cyclohexyl-phenyl-ketone (e.g. Irgacure 184 available from Ciba Specialty Chemicals), 2-methyl-2-morpholino (4-thiomethylphenyl)-1-propanone (e.g. Irgacure 907 available from Ciba Specialty Chemicals), 2-benzil-2-dimethylamino-1-(4-morpholinophenyl)-butanone (e.g. Irgacure 369 available from Ciba Specialty Chemicals), and oligomer of 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl] propanone (e.g. Esacure KIP available from Fratelli Lamberti s.p.a.).
The benzoinether photo polymerization initiators include, for example, benzoin, benzoin methylether, benzoin ethylether, benzoin isopropylether, and benzoin isobutylether.
The benzophenone photo polymerization initiators include, for example, benzophenone, o-benzoyl methyl benzoate, 4-phenyl benzophenone, 4-benzoyl-4xe2x80x2-methyldiphenylsulfide, 2,4,6-trimethyl benzophenone, and (4-benzoylbenzil) trimethylammoniumchloride.
The thioxantone photo polymerization initiators include, for example, 2- or 4-isopropylthioxantone, 2,4-diethylthioxantone and 2,4-dichlorothioxantone.
In addition to these, for example, methylphenylglyoxyester (Bycure 55 available from AKZO Nobel), 3,6-bis (2-morpholinoisobutyl)-9-butylcarbazole (A-Cure 3 available from Asahi Denka Kogyo) and Titanocene compound can be cited as the photo polymerization initiators that may be used.
These photo polymerization initiators may be used singly or in combination. To give actual examples, Irgacure-1700 (bis (2,6-dimethoxybenzoil)-2,4,4-trimethylpentyl phosphineoxide/2-hydroxy-2-methylphenylpropane-1-on=25/75%) and Irgacure-1800 (bis (2,6-dimethoxybenzoil)-2,4,4-trimethylpentyl phosphineoxide/1-hydroxycyclohexyl-phenylketone=25/75%) (both of which are available from Ciba Specialty Chemicals) can be cited as commercially available ones.
Preferably, 0.001-40 parts by weight, or preferably 0.01-20 parts by weight, of the photo polymerization initiator content is used per 100 parts by weight of the carboxyl modified resin of the saponified ethylene-vinyl acetate copolymer.
To promote photo polymerization reaction caused by the photo polymerization initiator, a variety of photo polymerization promoters, such as dialkylamino benzoic acids or derivatives thereof (e.g. 4-dimethylamino benzoic acid and 4-dimethylamino benzoate) and phosphine photo polymerization promoters (aryl phospine, such as triphenylphosphine, and phosphine compound, such as trialkylphosphine) may selectively be mixed, if required.
Preferably, 0.01-10 parts by weight of the polymerization promotor is used per 100 parts by weight of the ethylene unsaturated monomer.
Chlorinated polyolefin contained resin may be mixed in the aqueous emulsion composition thus produced. The mixture of chlorinated polyolefin contained resin enables the adhesiveness to be properly adjusted.
The chlorinated polyolefin resin itself or the mixture obtained by mixing chlorinated polyolefin resin with other polymer is used as chlorinated polyolefin contained resin. The chlorinated polyolefin resin used is not limited to any particular one. Specifically, the chlorinated polyolefin resins can be cited which are produced by chlorinating polyolefins, such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, polybutene, ethylene-vinyl acetate copolymer, styrene-butadiene copolymer and styrene-isoprene copolymer, or by chlorinating modified polyolefins, in which carboxyl group, hydroxyl group and acid anhydride are introduced in those polyolefins, by a known manner.
Of these chlorinated polyolefin resins, the chlorinated polyolefin resins produced by chlorinating polypropylene and/or polyethylene are preferably used, because they are easily available and also can provide improved adhesion. Further, the acid-anhydride-modified chlorinated polyolefin resin produced by modifying the chlorinated polyolefin resin by use of maleic anhydride can also be cited. The chlorinated polyolefin resin may selectively be used singly or by mixture of two or more.
Though a chlorine content of the chlorinated polyolefin resin used is not limited to any particular value, a chlorine content of 15-40 weight % can provide improved adhesion to a polyolefin substrate. A chlorine content of less than 15 weight % of the chlorinated polyolefin resin may cause reduction of its compatibility with the other resins to cause reduction of its membrane forming ability. On the other hand, a chlorine content of more than 40 weight % of the chlorinated polyolefin resin may cause reduction of its adhesion to the polyolefin substrate.
Preferably, the chlorinated polyolefin contained resin in the range of 1-1,000 parts by weight is used per 100 parts by weight of the carboxyl modified resin of the saponified ethylene-vinyl acetate copolymer in the total amount of chlorinated polyolefin contained resin.
Known additives, such as an oxidation inhibitor, an ultraviolet absorbent, a coloring agent and a colorant, may be added to the aqueous emulsion composition thus produced, depending on the intended purposes and uses. In addition, rosins or a silane coupling agent may be added to provide further improved adhesive strength, depending on the intended purposes and uses.
The rosins that may be used include, for example, thermoplastic resin with abietic acid as the chief ingredient, such as gum rosin, wood rosin, and tall oil rosin. To be more specific, for example, modified rosins, such as hydrogenerated rosin (dihydroabietic acid and tetrahydroabietic acid), dismutation rosin, dismutation hydrogenerated rosin and polymerized rosin (including partly polymerized rosin), rosin or modified rosins of alkylester, glycol ester, glycerin ester and pentaerythritol ester, and rosin modified polyester using rosin or modified rosin to a part of acid of polyester can be cited. The rosin modified polyester can be produced by reaction of glycidyl ester of rosin or modified rosin with a compound having carboxylic acid.
The rosins may be used singly or in combination of two or more. Preferably, the rosins in the range of 1-20 parts by weight, or preferably 5-15-parts by weight, is used per 100 parts by weight of the carboxyl modified resin of the saponified ethylene-vinyl acetate copolymer.
The silane coupling agents that may be used include, for example, epoxy silane, amino silane and vinyl silane. The epoxy silane is preferably used. The epoxy silanes that may be used include, for example, xcex3-glycidoxypropyl trimethoxy silane, xcex3-glycidoxypropyl triethoxy silane, xcex3-glycidoxypropyl methyldiethoxy silane, and xcex2-(3,4-epoxycyclohexyl) ethyltrimethoxy silane.
The silane coupling agents may be used singly or in combination of two or more. Preferably, the silane coupling agents in the range of 0.05-5 parts by weight, or preferably 0.1-1.0 parts by weight, is used per 100 parts by weight of the carboxyl modified resin of the saponified ethylene-vinyl acetate copolymer.
The aqueous emulsion composition thus produced of the present invention can be suitably used as adherent composition including primer and adhesive. The aqueous emulsion composition of the present invention has high adhesion strength for a variety of materials so that it can be used for the adhesive bonding of a variety of molded products including, for example, plastic films, plastic sheets, plastic foams, fibers, synthetic leathers and metals. In addition, since the emulsion composition of the present invention is aqueous, there is little danger of catching fire, so that good environmental sanitation is secured. Further, the aqueous emulsion composition of the present invention is excellent in initial adhesion, at-low-temperature adhesion, mechanical stability, water resistance and storage stability and thus can effectively be used in a variety of intended uses.
For the bonding by using the adherent composition of the present invention, the adherent composition can be applied, for example, to a substrate to be bonded by any known method. The adherent composition of the present invention can be used without limitation. For example, the adherent composition of the present invention may be used as the primer used in the pretreatment of the bonding or as the adhesive. Also, the adherent composition of the present invention may be used in such a manner as to be mixed in the primer or the adhesive. When the photo polymerization initiator is mixed in the adherent composition of the present invention, the mixture is preferably irradiated with ultraviolet light of e.g. 50-1,000 mJ/cm2.